Measurements of coronary velocity and reactive hyperemia in the coronary circulation of humans.

Abstract

An acceptable method for measuring phasic coronary velocity and reactive hyperemia in humans has not been available. We have developed a doppler probe which can be coupled to surface coronary vessel* at the time of cardiac surgery with a small suction cup. Phasic coronary velocity can be measured with a signal to noise ratio that exceeds 20:1. Animal studies have shown that the probe does not alter myocardial perfusion or cause tissue damage. In addition, changes in mean coronary velocity are closely related (r « 0.97) to changes in coronary flow over a wide range (15-400 ml/min). The characteristics of reactive hyperemia in the coronary circulation of dogs determined with the doppler system are similar to those obtained simultaneously with an electromagnetic flow meter. Transient occlusions of branch coronary vessels in patients with normal coronary arteries are not associated with significant changes in heart rate, left atrial, or mean arterial pressure. The characteristics of reactive hyperemia in normal vessels of 13 patients were as follows: although reactive hyperemia responses were demonstrable following 1 to 2-aecond coronary occlusions, maximal responses usually occurred with 20-second coronary occlusions; following 20 seconds of coronary occlusion, the ratio of peak to resting velocity was 5.8 ± 0.6 (mean ± SE); the ratio of repayment to debt area was 3.1 ± 0.2, and the duration of the reactive hyperemia response was 20.8 ± 0.3 seconds. These studies provide the first quantitative measurements of coronary reactive hyperemia in humans. Circ Res 49: [877][878][879][880][881][882][883][884][885][886][887][888][889][890][891] 1981

Reversal of Reflex-Induced Myocardial Ischemia by Median Nerve Stimulation

“…Changes in mean coronary blood velocity are directly correlated with changes in coronary blood flow. 21 Data are presented as meanϮSEM. The changes in hemodynamic and wall thickening data produced by BK administration in the partial and complete occlusion groups were analyzed by two-way repeated-measures ANOVA.…”

Effects of Isoflurane on Coronary Blood Flow Velocity in Young, Old and ApoE−/− Mice Measured by Doppler Ultrasound

“…Coronary flow reserve has been estimated in man during surgery (Marcus et al, 1981), in the cardiac catheterization laboratory (White et al, 1984;Wilson et al, 1985), and most recently in the echocardiography laboratory (Saraste et al, 2001;Voci et al, 2004) using the ratio of hyperemic to baseline flow velocity. The reported values are between 2.5 and 5.0 depending on the flow or velocity sensing method, the vasodilator, and the experimental or clinical conditions.…”

“…Higher H/B in Old mice-In man H/B is used to estimate the severity and significance of several cardiac pathologies including coronary artery disease which reduces hyperemic flow (Gould et al, 1974;Marcus et al, 1981;Marcus, 1983), and valvular disease which increases resting cardiac work and baseline flow (Marcus et al, 1982). Wieneke, et al (2006) studied several factors which might influence H/B in man and found that only age and baseline velocity influenced H/B in healthy individuals.…”

“…Thus, measurements of coronary flow or velocity have required the use of invasive methods such as implantable flow probes (Hartley and Cole, 1974) or coronary catheters (Cole and Hartley, 1977;Sibley et al, 1986;Wilson et al, 1985). In addition, coronary blood flow (even if it could be measured accurately) is often normal at rest even in the presence of severe coronary artery disease (Gould et al, 1974;Marcus et al, 1981). This problem is commonly addressed by administering a coronary vasodilator such as adenosine (Hoffman, 1984;Marcus, 1983) to increase blood flow and then measuring the ratio of maximum hyperemic flow to resting baseline flow as an index of coronary vascular reserve (Gould et al, 1974).…”

“…This problem is commonly addressed by administering a coronary vasodilator such as adenosine (Hoffman, 1984;Marcus, 1983) to increase blood flow and then measuring the ratio of maximum hyperemic flow to resting baseline flow as an index of coronary vascular reserve (Gould et al, 1974). Coronary vascular reserve has been shown to be reduced in the presence of coronary lesions due to a reduction in hyperemic flow (Marcus et al, 1981), and by other cardiac pathologies due to an increase in baseline flow (Marcus et al, 1982;Marcus, 1983).…”